Prosthetic device having a polyaryletherketone component with enhanced wettability and method for making the same

ABSTRACT

A prosthetic device having a polyaryletherketone component with a wettable surface is disclosed. The surface of the polyaryletherketone component has a surface chemistry which enhances the ability of tissues to grow directly thereon. An associated method for enhancing the wettability of a prosthetic device is also disclosed.

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application is a divisional application of U.S. patentapplication Ser. No. 10/108,852, filed on Mar. 28, 2002, now allowed.

TECHNICAL FIELD OF THE DISCLOSURE

[0002] The present disclosure relates generally to prosthetic devices,and more particularly to prosthetic devices having a polyaryletherketonecomponent with enhanced wettability.

BACKGROUND

[0003] Materials used to fabricate prosthetic devices, such as anorthopedic implant, need to possess certain mechanical and chemicalproperties in order to function and exist in contact with the biologicaltissue of a living organism. For example, these materials should possessthe appropriate mechanical/chemical properties so they do not induceundesirable reactions in the body such as blood clotting, tissue death,tumor formation, allergic reaction, foreign body reaction (rejection),and/or inflammatory reaction. In addition, the materials used tofabricate prosthetic devices should posses the appropriate strength,elasticity, permeability, and flexibility in order for the prostheticdevice to function properly for its intended purpose. Moreover, it isdesirable that these materials (i) sterilize easily and (ii)substantially maintain their physical properties during the time theprosthetic device remains in contact with the biological tissue.

[0004] There are a number of materials currently available which possessone or more of the above described characteristics. Accordingly, thesematerials can be utilized for fabricating prosthetic devices. However, adrawback to some of these materials is that they do not present asurface which is well suited for direct tissue growth (e.g. bone) ontoor into the prosthetic device. As such, prosthetic devices fabricatedfrom these materials have a decreased ability to form a suitably stablemechanical unit with the neighboring tissues (e.g. bone). Therefore,these prosthetic devices can become loose or unstable relative to theneighboring tissue which can result in the device functioning lessefficiently or not functioning at all. A loose or unstable prostheticdevice can also induce an excessive tissue response and cause thepatient discomfort and pain. Finally, a loose prosthetic device isdeemed to have failed, and thus has to be surgically removed whichfurther burdens the patient.

[0005] Accordingly, in light of the above discussion, a material forfabricating a prosthetic device which addresses the above describeddrawback is needed.

SUMMARY

[0006] In accordance with one exemplary embodiment, there is provided aprosthetic device. The prosthetic device includes a polyaryletherketonecomponent. The polyaryletherketone component has a surface, and thesurface has an tissuegenically effective amount of sulfonation thereon.

[0007] In accordance with another exemplary embodiment, there isprovided a prosthetic arrangement for implanting in the body of apatient. The prosthetic arrangement includes an orthopedic implantdevice having a polyaryletherketone component. The polyaryletherketonecomponent has a surface, and the surface has an tissuegenicallyeffective amount of sulfonation thereon.

[0008] In accordance with yet another exemplary embodiment, there isprovided an orthopedic device. The orthopedic device includes apolyaryletherketone component. The polyaryletherketone component has asurface, and the surface has an tissuegenically effective amount ofsulfonation thereon.

[0009] In accordance with still another exemplary embodiment, there isprovided a method of preparing a prosthetic device having apolyaryletherketone component. The method includes (a) contacting asurface of the polyaryletherketone component of the prosthetic devicewith a sulfonation agent and (b) sulfonating the surface of thepolyaryletherketone component.

[0010] In accordance with yet another exemplary embodiment, there isprovided a prosthetic device having a polyaryletherketone componentprepared by subjecting the polyaryletherketone component to asulfonation reaction.

[0011] In accordance with still another exemplary embodiment, there isprovided a method of preparing a prosthetic device which includes apolyaryletherketone component having a surface. The method includesreacting the surface of the polyaryletherketone component of theprosthetic device with a chemical so that the wettability of the surfaceis increased.

[0012] In accordance with yet another exemplary embodiment, there isprovided a prosthetic device. The prosthetic device includes apolyaryletherketone component. The polyaryletherketone component has asurface which has a wettability such that a contact angle of a bead ofwater positioned on the surface has a value less than 78°.

[0013] In accordance with still another exemplary embodiment, there isprovided a prosthetic device. The prosthetic device includes anorthopedic implant having a polyaryletherketone component. Thepolyaryletherketone component has a surface which has a wettability suchthat a contact angle of a bead of water positioned on the surface has avalue less than 780°.

[0014] In accordance with yet another exemplary embodiment, there isprovided a polyaryletherketone component. The polyaryletherketonecomponent includes a surface having a wettability such that a contactangle of a bead of water positioned on the surface has a value less than78°.

[0015] The above and other features of the present disclosure willbecome apparent from the following description and the attacheddrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The detailed description particularly refers to the accompanyingfigures in which:

[0017]FIG. 1 depicts an Energy-Dispersive X-Ray Analysis spectrum of apolyaryletherketone sample prior to being subjected to a sulfonationreaction;

[0018]FIG. 2 depicts an Energy-Dispersive X-Ray Analysis spectrum of apolyaryletherketone sample after being subjected to a sulfonationreaction neutralized with calcium hydroxide; and

[0019]FIG. 3 depicts an Energy-Dispersive X-Ray Analysis spectrum of apolyaryletherketone sample after being subjected to a sulfonationreaction neutralized with potassium hydroxide.

DETAILED DESCRIPTION OF THE DISCLOSURE

[0020] The present invention relates to prosthetic devices havingenhanced wettability and methods of making the same. The prostheticdevices described herein can be utilized as endoprosthetic devicesconfigured to be implanted within the body of a patient. In particular,the prosthetic devices described herein can be utilized as orthopedicdevices, such as an orthopedic implant of any type, condition, shape, orconfiguration. For example, these orthopedic implants may be utilized ina number of joint replacement or repair procedures such as surgicalprocedures associated with the hip, shoulders, knees, ankles, knuckles,or any other joint.

[0021] It should be appreciated that the prosthetic devices describedherein include a polyaryletherketone component. It should also beappreciated that only a portion of the prosthetic device can be madefrom the polyaryletherketone component, or the entire prosthetic devicecan be made from the polyaryletherketone component. What is meant hereinby a polyaryletherketone component is that the component includes one ormore polymers from the polyaryletherketone family, including, but notlimited to, a polyaryletherketone which contains repeating units of thefollowing general formula:

[0022] where A is a direct link, a sulfur atom, a divalent hydrocarbonradical or a group —Q-(Ar-Q¹)_(n) in which Q is —CO—, —SO₂—, or —O—, Q¹is —O—, and Ar is a divalent aromatic radical and n is 0, 1, 2 or 3. Inparticular, the polyaryletherketone can contain repeating units of:

[0023] Polyaryletherketones which can be utilized in the presentinvention are described in U.S. Pat. No. 4,320,224 which is incorporatedherein by reference. In addition, polyaryletherketones which can beutilized in the present invention are commercially available fromVictrex plc, located in Lancashire, England. For example, apolyaryetheretherketone (also known as PEEK™) having theoxy-1,4-phenylene-oxy-1,4-phenylene-carbonyl-1,4-phenylene repeat unit,which is shown again below, is commercially available from Victrex pic.in various grades (e.g. 450G, 381G, and 150G)

[0024] It should be appreciated that a prosthetic device of the presentinvention is subject to a chemical reaction which increases its“wettability”. What is meant herein by “wettability” is the ability of asolid surface (e.g. the surface of the polyaryletherketone component) tobe wetted when in contact with a liquid (e.g. water); that is thesurface tension of the liquid is reduced so the liquid spreads over thesurface. In particular, a surface of the polyaryletherketone componentof the prosthetic device is reacted with a chemical so that thewettability of the surface is increased. (Note that, as used herein, theterm “surface” includes the interior surface of pores or cavitiesdefined in the prosthetic device. In particular the interior surface ofpores or cavities defined in the polyaryletherketone component of theprosthetic device.) For example, the surface of the polyaryletherketonecomponent of the prosthetic device can be reacted with a chemical sothat the hydrophilicity of the surface is increased. What is meantherein by “hydrophilicity” is a measure of the affinity of the solidsurface (e.g. the surface of the polyaryletherketone component) forattracting, adsorbing, or absorbing water.

[0025] The increase in the wettability of the surface of apolyaryletherketone component as a result of the aforementioned chemicalreaction can be measured by any known appropriate technique. Forexample, one technique for measuring the increase in wettability of thesurface of the polyaryletherketone component is to measure the contactangle θ of a bead of liquid (e.g. water) at the interface of the bead ofliquid and the surface of the polyaryletherketone component. Forexample, the lower the contact angle θ of a bead of water at theinterface of the bead of water and the surface of thepolyaryletherketone component, the greater the wettability of thesurface of the polyaryletherketone component. Preferably, the surface ofthe polyaryletherketone component of the prosthetic device is reactedwith a chemical so that the contact angle of a bead of water at theinterface of the bead of water and the surface of thepolyaryletherketone component is less than 78°. For example, afterincreasing the wettability of the surface of the polyaryletherketonecomponent, it is preferable that the aforementioned contact anglebetween the bead of water and the surface is within a range of about 77°to about 40°. For example, contact angles within a range of about 60° toabout 40° are particularly desirable. However, it should also beappreciated that contact angles between a bead of water and a surface ofa polyaryletherketone component which are less than about 40°, forexample less than about 30°, are even more preferable as long as thewettability increasing process the surface of the polyaryletherketonecomponent is subjected to satisfies the criteria discussed below.

[0026] Now turning to the above discussed chemical reaction, it shouldbe appreciated that any appropriate reaction which chemically alters thesurface of the polyaryletherketone component so as to increase itswettability can be utilized. However, it should also be appreciated thatthe chemical alteration of the surface of the polyaryletherketonecomponent should not adversely affect, to any significant degree, itsability to be implanted in the body of a living organism, such as ahuman patient. In other words, after the chemical alteration thepolyaryletherketone component should be “biocompatible”. As used herein,the polyaryletherketone component is characterized as being“biocompatible” if it is capable of functioning or existing in contactwith biological fluid and/or tissue of a living organism with a netbeneficial affect on the living organism. In addition, the abovedescribed chemical alteration should not adversely affect, to anysignificant degree, the desirable chemical and/or mechanical propertiesof the polyaryletherketone component. For example, the chemicalalteration should not erode the surface of the polyaryletherketone toany significant degree.

[0027] One method of increasing the wettability of the prosthetic deviceis to react the surface of the polyaryletherketone component with achemical so that polar functional groups are disposed on the surface.The greater the number of polar groups disposed on the surface, thegreater the wettability of the surface. These polar functional groupscan be disposed on the surface via the formation of covalent bondsbetween the polar functional groups and chemical groups present on thesurface of the polyaryletherketone component. However, any otherappropriate chemical bonding mechanism (e.g. ionic) can be utilized todispose the polar functional groups on the component surface as long asthe bonding mechanism satisfies the aforementioned criteria ofincreasing the surface wettability while not adversely affecting, to anysignificant degree, the component's (i) ability to be implanted into aliving body and/or (ii) its mechanical properties.

[0028] The above discussed wettability enhancing chemical reaction canbe performed on the assembled prosthetic device or on thepolyaryletherketone components prior to assembly into the prostheticdevice. In addition, the wettability enhancing chemical reaction can beperformed on polyaryletherketones in various physical states, includingbut not limited to, polyaryletherketone resins used to fabricate thepolyaryletherketone component, polyaryletherketone composites used tofabricate the polyaryletherketone component, and porouspolyaryletherketone structures used to fabricate the polyaryletherketonecomponent.

[0029] An example of one chemical reaction which can be used to increasethe wettability of the prosthetic device while satisfying the abovediscussed criteria is sulfonation. What is meant herein by sulfonationis the substitution of —SO₃H groups from a sulfonation agent forhydrogen atoms. For example, the sulfonation of the surface of apolyaryletherketone component which includes the repeating unit

[0030] can be illustrated by the following equation:

[0031] and salts thereof. Examples of sulfonation agents which can beutilized in the above illustrated equation include, but are not limitedto, sulfuric acid (>95%), fuming sulfuric acid, and sulfur trioxide.

[0032] The sulfonation of a surface of a polyaryletherketone componentcan be accomplished by contacting the surface with a sulfonation agentat about room temperature up to a temperature of about 80° C. for a timeperiod between about 5 minutes up to about 20 minutes. The particularsulfonation reaction conditions (e.g. temperature, time period,concentration of the sulfonation agent) utilized will depend upon thespecific polyaryletherketone surface being sulfonated, the particularsulfonation agent selected, and the degree of sulfonation desired. Forexample, some members of the polyaryletherketone family will requiremore vigorous sulfonation conditions to achieve the desired degree ofsulfonation, while other members will require less vigorous sulfonationconditions, depending upon, for example, the chemical nature of thepolyaryletherketone component.

[0033] An example, of a sulfonation reaction is described below. Samplesof Victrex 450G PEEK™ films (0.004 inch) were cleaned with isopropylalcohol and vacuum dried at 60° C. prior to being subjected to thesulfonation reaction. Thereafter each PEEK™ film sample was placed incontact with 96.5% sulfuric acid at room temperature. Each PEEK™ filmwas kept in contact with the sulfuric acid for a time period of at least10 minutes. At this point (i.e. 10 minutes) some of the PEEK™ filmsamples were removed from the sulfuric acid and thoroughly washed withwater. After the aqueous wash, the PEEK™ film samples were neutralizedwith a 0.5N potassium hydroxide solution, a saturated calcium hydroxidesolution, or a 0.25 sodium citrate solution. The neutralized PEEK™ filmsamples were then rinsed with water and vacuum dried at 60° C. prior tosurface characterization. The remaining PEEK™ film samples were kept incontact with the sulfuric acid for various times up to about 20 minutes.When these PEEK™ film samples were removed from the sulfuric acid theywere neutralized and dried in the same manner as described above priorto surface characterization.

[0034] The Energy-Dispersive X-Ray Analysis (EDXA) was utilized forsurface characterization of the PEEK™ samples. In particular, the EDXAspectrum of the above described PEEK™ films were taken before and afterbeing subjected to the sulfonation reaction. In particular, FIG. 1illustrates the EDXA spectrum of a PEEK™ film prior to being subjectedto the sulfonation reaction. As shown in the spectrum of FIG. 1, carbonand oxygen are detected by the EDXA analysis which is consistent withthe surface characteristics of a PEEK™ sample prior to sulfonation. Withrespect to FIG. 2, it illustrates the EDXA spectrum of a PEEK™ filmafter being subjected to the sulfonation reaction and then neutralizedwith a calcium hydroxide solution. As shown in the spectrum of FIG. 2,the EDXA analysis detects carbon, oxygen, sulfur, and calcium which isconsistent with the expected surface characteristics of a PEEK™ sampleafter being subjected to sulfonation and then neutralized with a calciumhydroxide solution. FIG. 3 illustrates the EDXA spectrum of a PEEK™ filmafter being subjected to the sulfonation reaction and then neutralizedwith a potassium hydroxide solution. As shown in the spectrum of FIG. 3,the EDXA analysis detects carbon, oxygen, sulfur, and potassium which isconsistent with the expected surface characteristics of a PEEK™ sampleafter being subjected to sulfonation and then neutralized with apotassium hydroxide solution.

[0035] With respect to the surface wettability of PEEK™ sulfonated inthe above described manner, contact angles of about 51° with respect toa bead of water were obtained with these samples. This is in contrast toan unsulfonated PEEK™ sample which has a contact angle of 78° or morewith respect to a bead of water. Accordingly, the above describedsulfonation reaction increased the surface wettability of these PEEK™samples.

[0036] It should be understood that enhancing the wettability of asurface of a prosthetic device results in the surface becoming“tissuegenic”. What is meant herein by a “tissuegenic” surface is thatthe surface has a capacity, or an increased capacity, for tissue to growdirectly onto or into the surface. In other words, tissues have agreater affinity for a tissuegenic surface. Tissues which can growdirectly onto or into a tissuegenic surface include, but are not limitedto, bone, cartilage, and tendon.

[0037] As discussed above, one way of enhancing the wettability of asurface, and thereby rendering the surface “tissuegenic”, is to disposea sufficient amount of polar functional groups on the surface via achemical reaction. Accordingly, a surface of a polyaryletherketonecomponent having an tissuegenically effective amount of polar functionalgroups disposed thereon will have a capacity, or an increased capacity,for tissue, such as bone, to grow directly onto or into the surface. Forexample, a polyaryletherketone component surface having antissuegenically effective amount of sulfonation thereon (i.e. aneffective amount of —SO₃H groups and salts thereof disposed thereon) hasa capacity, or an increased capacity as compared to the surface prior tothe sulfonation, for tissue (e.g. bone) to grow directly onto or intothe surface.

[0038] The tissuegenicity, or the increase in the tissuegenicity, of asurface of a polyaryletherketone component as a result of theaforementioned chemical reaction can be measured by any knownappropriate technique. For example, one technique for measuring thetissuegenicity, or the increase in tissuegenicity, of the surface of thepolyaryletherketone component is to measure the shear strength ortensile strength of the interface between the surface of thepolyaryletherketone component and the contacting tissue (e.g. bone). Thegreater the shear strength or tensile strength of the interface betweenthe surface of the polyaryletherketone component and the contactingtissue the greater the surface tissuegenicity. Accordingly, a prostheticdevice having a polyaryletherketone component with a tissuegenic surfacehas an enhanced capacity to form a suitably stable mechanical unit withthe neighboring tissues (e.g. bone). Therefore, these prosthetic deviceshave a decreased probability of becoming loose or unstable relative tothe neighboring tissue and thereby functioning less efficiently or notfunctioning at all.

[0039] While the disclosure is susceptible to various modifications andalternative forms, specific exemplary embodiments thereof have beenshown by way of example in the drawings and has herein been described indetail. It should be understood, however, that there is no intent tolimit the disclosure to the particular forms disclosed, but on thecontrary, the intention is to cover all modifications, equivalents, andalternatives falling within the spirit and scope of the disclosure.

[0040] There are a plurality of advantages of the present disclosurearising from the various features of the apparatus and methods describedherein. It will be noted that alternative embodiments of the apparatusand methods of the present disclosure may not include all of thefeatures described yet still benefit from at least some of theadvantages of such features. Those of ordinary skill in the art mayreadily devise their own implementations of an apparatus and method thatincorporate one or more of the features of the present disclosure andfall within the spirit and scope of the present disclosure.

1. A prosthetic device, comprising: a polyaryletherketone component,wherein said polyaryletherketone component has a surface, and saidsurface has an tissuegenically effective amount of sulfonation thereon.2. The device of claim 1, wherein: said polyaryletherketone componentincludes repeating units of

where A is a direct link, a sulfur atom, a divalent hydrocarbon radicalor a group —Q-(Ar-Q¹)_(n) in which Q is —CO—, —SO₂—, or —O—, Q¹ is —O—,and Ar is a divalent aromatic radical and n is 0, 1, 2 or
 3. 3. Thedevice of claim 1, wherein: said polyaryletherketone component includesrepeating units of


4. The device of claim 1, wherein: said polyaryletherketone componentincludes repeating units of


5. The device of claim 1, wherein: said polyaryletherketone componentincludes units of

and/or salts thereof.
 6. A prosthetic arrangement for implanting in thebody of a patient, comprising: an orthopedic implant device having apolyaryletherketone component, wherein said polyaryletherketonecomponent has a surface, and said surface has an tissuegenicallyeffective amount of sulfonation thereon.
 7. The arrangement of claim 6wherein: said polyaryletherketone component includes repeating units of

where A is a direct link, a sulfur atom, a divalent hydrocarbon radicalor a group —Q-(Ar-Q¹)_(n) in which Q is —CO—, —SO₂—, or —O—, Q¹ is —O—,and Ar is a divalent aromatic radical and n is 0, 1,2or
 3. 8. Thearrangement of claim 6, wherein: said polyaryletherketone componentincludes repeating units of


9. The arrangement of claim 6, wherein: said polyaryletherketonecomponent includes repeating units of


10. The arrangement of claim 6, wherein: said polyaryletherketonecomponent includes units of

and/or salts thereof.
 11. An orthopedic device, comprising: apolyaryletherketone component, wherein said polyaryletherketonecomponent has a surface, and said surface has an tissuegenicallyeffective amount of sulfonation thereon.
 12. The device of claim 11,wherein: said polyaryletherketone component includes repeating units of

where A is a direct link , a sulfur atom, a divalent hydrocarbon radicalor a group —Q-(Ar-Q¹)_(n) in which Q is —CO—, —SO₂—, or —O—, Q¹ is —O—,and Ar is a divalent aromatic radical and n is 0, 1, 2 or
 3. 13. Thedevice of claim 11, wherein: said polyaryletherketone component includesrepeating units of


14. The device of claim 11, wherein: said polyaryletherketone componentincludes repeating units of


15. The device of claim 11, wherein: said polyaryletherketone componentincludes repeating units of

and/or salts thereof.
 16. A prosthetic device having apolyaryletherketone component prepared by subjecting saidpolyaryletherketone component to a sulfonation reaction.